Effect of cultivar on the quality of flax and hemp grown in South Africa
- Authors: Blouw, Langa Sunshine
- Date: 2012
- Subjects: Hemp -- South Africa , Flaxseed -- South Africa , Plant varieties , Textile industry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9387 , http://hdl.handle.net/10948/d1010997 , Hemp -- South Africa , Flaxseed -- South Africa , Plant varieties , Textile industry
- Description: Bast fibrous renewable materials, as commercial crops for the manufacture of textile based and other products, have been used for thousands of years to satisfy certain human needs, such as for shelter, clothing, source of energy and tools, and to sustain the livelihood of many communities in countries, such as in Asia, Europe and Africa. Concern for the environment has led to a number of global initiatives that favour the use of natural fibres. It is forecast that the global fibre demand by 2050 will be 130 million tonnes, which the cotton and synthetic fibre production will not be able to meet. Other than the environmental concerns, the renewed global interest in natural fibres, such as flax and hemp, forms part of a strategy to satisfy the fibre demand. South Africa, notwithstanding the fact that the flax and hemp industries have long been established for thousands of years in Europe, Asia and Egypt (Africa), has no history of the breeding, growing, processing and production of these cash crops. The renewed global interest in these crops has also stimulated interest from South Africa with respect to the development of a flax and hemp fibre industry so as to address some of the socio-economic challenges confronting the country today in its attempts to bring about real development in the rural areas through the cultivation and complete beneficiation of these fibre crops. In this regard, the relevant stakeholders, namely government, research councils, tertiary education institutions, farmers and communities worked together to investigate whether South Africa has the agronomic and climatic conditions, technical expertise as well as the necessary processing and production infrastructure to support the development of a local flax and hemp agro-industry. The purpose of this study was firstly to evaluate the performance of EU flax and hemp cultivars grown under different agronomic conditions in South Africa, and their effect on straw biomass yield, fibre yield and total fibre yield per hectare as well as associated fibre properties, and secondly to undertake mechanical fibre modification trials aimed at producing flax and hemp fibres with fibre diameters close to those of cotton. The minimum fibre diameter targeted being 20μm. In accordance with the project objectives and work plan, selected dew retted flax and hemp straw samples from the various planting sites selected by the Agriculture Research Council – Institute for Industrial Crops, representing all the agronomic conditions under investigation, were taken to the CSIR for fibre extraction and testing. A relatively inexpensive and easy to operate Russian designed and manufactured machine, the CMT-200M breaker-cum-scutcher, was used for fibre extraction and the resultant extracted fibre bundles were further refined, using a steel comb, to obtain optimal fibre separation before their physical and chemical properties were evaluated. Results obtained in this research study proved that the climatic and agronomic conditions in South Africa were suitable for the cultivation of flax and hemp, notwithstanding the fact that the fibre yields achieved for hemp were lower than the minimum criteria of 23 percent, and that for flax only just exceeded the 25 percent minimum. The lack of local technical expertise on the growing and retting of flax and hemp, contributed to the low fibre yields. The planting parameters which were found to produce good results for the cultivation of hemp were the October planting date, using a row spacing of between 12.5 to 25 cm, with a seeding density of between 80 – 100kg, and the application of 50 – 100kg nitrogen fertiliser. The use of extra artificial lighting and herbicide treatment did not appear to beneficially improve the hemp fibre yields. Similar considerations for flax cultivation in the Southern Cape region, particularly Oudtshoorn and Outeniqua, indicated that May to July planting dates, using inter-row spacing of 25cm and sowing density of 63kg seed.haˉ¹, produced a fibre yield and total fibre yield per hectare above the minimum values of 25 percent and 0,8 tonnes per hectare, respectively, quoted in the literature.
- Full Text:
- Date Issued: 2012
- Authors: Blouw, Langa Sunshine
- Date: 2012
- Subjects: Hemp -- South Africa , Flaxseed -- South Africa , Plant varieties , Textile industry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9387 , http://hdl.handle.net/10948/d1010997 , Hemp -- South Africa , Flaxseed -- South Africa , Plant varieties , Textile industry
- Description: Bast fibrous renewable materials, as commercial crops for the manufacture of textile based and other products, have been used for thousands of years to satisfy certain human needs, such as for shelter, clothing, source of energy and tools, and to sustain the livelihood of many communities in countries, such as in Asia, Europe and Africa. Concern for the environment has led to a number of global initiatives that favour the use of natural fibres. It is forecast that the global fibre demand by 2050 will be 130 million tonnes, which the cotton and synthetic fibre production will not be able to meet. Other than the environmental concerns, the renewed global interest in natural fibres, such as flax and hemp, forms part of a strategy to satisfy the fibre demand. South Africa, notwithstanding the fact that the flax and hemp industries have long been established for thousands of years in Europe, Asia and Egypt (Africa), has no history of the breeding, growing, processing and production of these cash crops. The renewed global interest in these crops has also stimulated interest from South Africa with respect to the development of a flax and hemp fibre industry so as to address some of the socio-economic challenges confronting the country today in its attempts to bring about real development in the rural areas through the cultivation and complete beneficiation of these fibre crops. In this regard, the relevant stakeholders, namely government, research councils, tertiary education institutions, farmers and communities worked together to investigate whether South Africa has the agronomic and climatic conditions, technical expertise as well as the necessary processing and production infrastructure to support the development of a local flax and hemp agro-industry. The purpose of this study was firstly to evaluate the performance of EU flax and hemp cultivars grown under different agronomic conditions in South Africa, and their effect on straw biomass yield, fibre yield and total fibre yield per hectare as well as associated fibre properties, and secondly to undertake mechanical fibre modification trials aimed at producing flax and hemp fibres with fibre diameters close to those of cotton. The minimum fibre diameter targeted being 20μm. In accordance with the project objectives and work plan, selected dew retted flax and hemp straw samples from the various planting sites selected by the Agriculture Research Council – Institute for Industrial Crops, representing all the agronomic conditions under investigation, were taken to the CSIR for fibre extraction and testing. A relatively inexpensive and easy to operate Russian designed and manufactured machine, the CMT-200M breaker-cum-scutcher, was used for fibre extraction and the resultant extracted fibre bundles were further refined, using a steel comb, to obtain optimal fibre separation before their physical and chemical properties were evaluated. Results obtained in this research study proved that the climatic and agronomic conditions in South Africa were suitable for the cultivation of flax and hemp, notwithstanding the fact that the fibre yields achieved for hemp were lower than the minimum criteria of 23 percent, and that for flax only just exceeded the 25 percent minimum. The lack of local technical expertise on the growing and retting of flax and hemp, contributed to the low fibre yields. The planting parameters which were found to produce good results for the cultivation of hemp were the October planting date, using a row spacing of between 12.5 to 25 cm, with a seeding density of between 80 – 100kg, and the application of 50 – 100kg nitrogen fertiliser. The use of extra artificial lighting and herbicide treatment did not appear to beneficially improve the hemp fibre yields. Similar considerations for flax cultivation in the Southern Cape region, particularly Oudtshoorn and Outeniqua, indicated that May to July planting dates, using inter-row spacing of 25cm and sowing density of 63kg seed.haˉ¹, produced a fibre yield and total fibre yield per hectare above the minimum values of 25 percent and 0,8 tonnes per hectare, respectively, quoted in the literature.
- Full Text:
- Date Issued: 2012
Effective and efficient performance management in local government, with reference to the Cacadu District Municipality
- Authors: Asmah-Andoh, Kwame
- Date: 2012
- Subjects: Performance -- Management , Performance standards -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape , Employees -- Rating of -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8161 , http://hdl.handle.net/10948/1633 , Performance -- Management , Performance standards -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape , Employees -- Rating of -- South Africa
- Description: This study examined the existing levels of effectiveness and efficiency in local government with the application of performance management systems in the provision of municipal services. The provision of district-wide water services in Cacadu District Municipality in the Province of the Eastern Cape, South Africa is used for particular reference. Local government reforms after 1994 led to the creation of the district municipality (which groups together a number of local municipalities) to drive district-wide services provision, the introduction of systematic services provision standards and performance management as part of management reforms in municipalities. The problem for the research deals with how the Cacadu District Council and the councils of the local municipalities within the district are collaborating in using performance management systems, what effects this could have on programmes and services provision and how communication of performance information would improve service provision. Conceptual and practical difficulties encountered in effective and efficient utilisation and some obstacles that contribute to impeding progress in the use of performance management systems in municipalities were analysed. The qualitative research included a review of documents from the public administration and management literature; discourse analysis of interviews with municipal councilors and appointed officials, community members and provincial managers. The document review included a review of municipal documents that incorporated performance management or described development and use of performance management systems. It also included the legal frameworks and statutory requirements for municipal government and administration. All the responding municipal councils within the Cacadu District Municipality reported using performance management over the past five years yet little empirical evidence explains usage for district-wide programmes and services provision. Research shows that a comprehensive performance management approach to programmes and services has a more effective and efficient impact on service improvement than utilisation of personnnel appraisal (Ammons and Rivenbark, 2005). Despite the expected benefits, personnel performance appraisal is often flawed and the need exists in the district municipal model to develop and utilise performance management systems that validly assess the work performance of personnel (Hindo, 2010). Performance management system utilisation in decision making management is more related to the long-term benefits of effectiveness and efficiency than personnel appraisal for performance rewards and reporting. To overcome and address a situation of managing performance without a performance management system the study proposes a programme performance measurement and management system which incorporates information on management inputs, programme-specific data and citizens' feedback for outcomes and impact of the service. The suggested design for district-wide and specific municipal services provision elicit and provide relevant and appropriate performance information for management, decision-making and accountability to community. The effectiveness of the proposed system is to provide information for decision-making, long-term planning, strategic management and accountability reporting. The proposal is built on the exisiting method and thus efficient in the utilisation of resources. This has implications both for the theory of Public Administration and Management and the practical application of performamce management in public institutions. The study explicity provides a Public Administration perspective on management in a multi-municipal district context with different authorities. The study contributes to the theory of administrative policy and management context of the municipality with special attention to functions for which different authorities are responsible and the role of a performance system for better insught into managing overlapping authority, gaps and duplications. A central purpose of public management research is to theorise and influence practice. The practical utilisation of the proposed method is intended to assist managers and politicians with better understanding of a sustainable performance management system.
- Full Text:
- Date Issued: 2012
- Authors: Asmah-Andoh, Kwame
- Date: 2012
- Subjects: Performance -- Management , Performance standards -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape , Employees -- Rating of -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8161 , http://hdl.handle.net/10948/1633 , Performance -- Management , Performance standards -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape , Employees -- Rating of -- South Africa
- Description: This study examined the existing levels of effectiveness and efficiency in local government with the application of performance management systems in the provision of municipal services. The provision of district-wide water services in Cacadu District Municipality in the Province of the Eastern Cape, South Africa is used for particular reference. Local government reforms after 1994 led to the creation of the district municipality (which groups together a number of local municipalities) to drive district-wide services provision, the introduction of systematic services provision standards and performance management as part of management reforms in municipalities. The problem for the research deals with how the Cacadu District Council and the councils of the local municipalities within the district are collaborating in using performance management systems, what effects this could have on programmes and services provision and how communication of performance information would improve service provision. Conceptual and practical difficulties encountered in effective and efficient utilisation and some obstacles that contribute to impeding progress in the use of performance management systems in municipalities were analysed. The qualitative research included a review of documents from the public administration and management literature; discourse analysis of interviews with municipal councilors and appointed officials, community members and provincial managers. The document review included a review of municipal documents that incorporated performance management or described development and use of performance management systems. It also included the legal frameworks and statutory requirements for municipal government and administration. All the responding municipal councils within the Cacadu District Municipality reported using performance management over the past five years yet little empirical evidence explains usage for district-wide programmes and services provision. Research shows that a comprehensive performance management approach to programmes and services has a more effective and efficient impact on service improvement than utilisation of personnnel appraisal (Ammons and Rivenbark, 2005). Despite the expected benefits, personnel performance appraisal is often flawed and the need exists in the district municipal model to develop and utilise performance management systems that validly assess the work performance of personnel (Hindo, 2010). Performance management system utilisation in decision making management is more related to the long-term benefits of effectiveness and efficiency than personnel appraisal for performance rewards and reporting. To overcome and address a situation of managing performance without a performance management system the study proposes a programme performance measurement and management system which incorporates information on management inputs, programme-specific data and citizens' feedback for outcomes and impact of the service. The suggested design for district-wide and specific municipal services provision elicit and provide relevant and appropriate performance information for management, decision-making and accountability to community. The effectiveness of the proposed system is to provide information for decision-making, long-term planning, strategic management and accountability reporting. The proposal is built on the exisiting method and thus efficient in the utilisation of resources. This has implications both for the theory of Public Administration and Management and the practical application of performamce management in public institutions. The study explicity provides a Public Administration perspective on management in a multi-municipal district context with different authorities. The study contributes to the theory of administrative policy and management context of the municipality with special attention to functions for which different authorities are responsible and the role of a performance system for better insught into managing overlapping authority, gaps and duplications. A central purpose of public management research is to theorise and influence practice. The practical utilisation of the proposed method is intended to assist managers and politicians with better understanding of a sustainable performance management system.
- Full Text:
- Date Issued: 2012
Electrochemical sensing and immunosensing using metallophthalocyanines and biomolecular modified surfaces
- Authors: Mashazi, Philani Nkosinathi
- Date: 2012
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Measles -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5580 , http://hdl.handle.net/10962/d1018248
- Description: The synthesis of cobalt and manganese phthalocyanine complexes bearing eight hexylthio and four amino substituents was carried out. The formation of thin films of these complexes using different modification methods was also studied. Hexylthio functionalized metallophthalocyanine complexes were immobilized onto gold electrode surfaces using the self-assembly techniques. Surface modifications using cobalt and manganese tetraamino phthalocyanine as polymers, monolayers (onto electrografted surfaces) and as carbon nanotube – metallophthalocyanine conjugates was also carried out. The new method of modifying gold electrodes with metal tetraamino phthalocyanine complexes was investigated. The modified electrode surfaces were studied for their electrocatalytic properties and as potential electrochemical sensors for the detection of hydrogen peroxide (H₂O₂). The limits of detection for the H₂O₂ were of the orders of ~10⁻⁷ M for all the modified electrodes. The modified electrodes gave very good analytical parameters; such as good sensitivity, linearity at studied concentration range and well-defined analytical peaks with increased current densities. The modification methods were reproducible, highly conducting thin films were formed and the modified electrodes were very stable. The design of electrochemical immunosensors for the detection of measles-specific antibodies was also carried out. The modified surface with measles-antigen as sensing element was accomplished using covalent immobilization for an intimate connection of the measles-antigen as a sensing layer onto an electrode surface. Two methods of detecting measles-specific antibodies were investigated and these methods were based on electrochemical impedance, i.e. label-free detection, and voltammetric method using horse-radish peroxidase (HRP) labeled antibody as a reporter. The detection of measles-specific antibodies was accomplished using both these methods. The potential applications of the designed immunosensor were evaluated in real samples (human and newborn calf serum) and the electrodes could detect the antibodies in the complex sample matrix with ease.
- Full Text:
- Date Issued: 2012
- Authors: Mashazi, Philani Nkosinathi
- Date: 2012
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Measles -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5580 , http://hdl.handle.net/10962/d1018248
- Description: The synthesis of cobalt and manganese phthalocyanine complexes bearing eight hexylthio and four amino substituents was carried out. The formation of thin films of these complexes using different modification methods was also studied. Hexylthio functionalized metallophthalocyanine complexes were immobilized onto gold electrode surfaces using the self-assembly techniques. Surface modifications using cobalt and manganese tetraamino phthalocyanine as polymers, monolayers (onto electrografted surfaces) and as carbon nanotube – metallophthalocyanine conjugates was also carried out. The new method of modifying gold electrodes with metal tetraamino phthalocyanine complexes was investigated. The modified electrode surfaces were studied for their electrocatalytic properties and as potential electrochemical sensors for the detection of hydrogen peroxide (H₂O₂). The limits of detection for the H₂O₂ were of the orders of ~10⁻⁷ M for all the modified electrodes. The modified electrodes gave very good analytical parameters; such as good sensitivity, linearity at studied concentration range and well-defined analytical peaks with increased current densities. The modification methods were reproducible, highly conducting thin films were formed and the modified electrodes were very stable. The design of electrochemical immunosensors for the detection of measles-specific antibodies was also carried out. The modified surface with measles-antigen as sensing element was accomplished using covalent immobilization for an intimate connection of the measles-antigen as a sensing layer onto an electrode surface. Two methods of detecting measles-specific antibodies were investigated and these methods were based on electrochemical impedance, i.e. label-free detection, and voltammetric method using horse-radish peroxidase (HRP) labeled antibody as a reporter. The detection of measles-specific antibodies was accomplished using both these methods. The potential applications of the designed immunosensor were evaluated in real samples (human and newborn calf serum) and the electrodes could detect the antibodies in the complex sample matrix with ease.
- Full Text:
- Date Issued: 2012
Electrochemistry and photophysicochemical studies of titanium, tantalum and vanadium phthalocyanines in the presence of nanomaterials
- Authors: Chauke, Vongani Portia
- Date: 2012
- Subjects: Phthalocyanines -- Synthesis Electrochemistry Titanium Tantalum Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4313 , http://hdl.handle.net/10962/d1004971
- Description: The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.
- Full Text:
- Date Issued: 2012
- Authors: Chauke, Vongani Portia
- Date: 2012
- Subjects: Phthalocyanines -- Synthesis Electrochemistry Titanium Tantalum Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4313 , http://hdl.handle.net/10962/d1004971
- Description: The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.
- Full Text:
- Date Issued: 2012
Electrospun nanofibers : an alternative sorbent material for solid phase extraction
- Chigome, Samuel, Samuel Chigome
- Authors: Chigome, Samuel , Samuel Chigome
- Date: 2012 , 2012-03-26
- Subjects: Nanofibers -- Research Electrospinning -- Research Sorbents -- Research Extraction (Chemistry) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4314 , http://hdl.handle.net/10962/d1004972
- Description: The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).
- Full Text:
- Date Issued: 2012
- Authors: Chigome, Samuel , Samuel Chigome
- Date: 2012 , 2012-03-26
- Subjects: Nanofibers -- Research Electrospinning -- Research Sorbents -- Research Extraction (Chemistry) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4314 , http://hdl.handle.net/10962/d1004972
- Description: The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).
- Full Text:
- Date Issued: 2012
Empirical modelling of the solar wind influence on Pc3 pulsation activity
- Authors: Lotz, Stefanus Ignatius
- Date: 2012
- Subjects: Solar wind -- Research Solar activity -- Research Stellar oscillations -- Research , Magnetospheric radio wave propagation , Interplanetary magnetic fields
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5464 , http://hdl.handle.net/10962/d1005249
- Description: Geomagnetic pulsations are ultra-low frequency (ULF) oscillations of the geomagnetic field that have been observed in the magnetosphere and on the Earth since the 1800’s. In the 1960’s in situ observations of the solar wind suggested that the source of pulsation activity must lie beyond the magnetosphere. In this work the influence of several solar wind plasma and interplanetary magnetic field (IMF) parameters on Pc3 pulsations are studied. Pc3 pulsations are a class of geomagnetic pulsations with frequency ranging between 22 and 100 mHz. A large dataset of solar wind and pulsation measurements is employed to develop two empirical models capable of predicting the Pc3 index (an indication of Pc3 intensity) at one hour and five minute time resolution, respectively. The models are based on artificial neural networks, due to their ability to model highly non-linear interactions between dependent and independent variables. A robust, iterative process is followed to find and rank the set of solar wind input parameters that optimally predict Pc3 activity. According to the parameter selection process the input parameters to the low resolution model (1 hour data) are, in order of importance, solar wind speed, a pair of time-based parameters, dynamic solar wind pressure, and the IMF orientation with respect to the Sun-Earth line (i.e. the cone angle). Input parameters to the high resolution model (5 minute data) are solar wind speed, cone angle, solar wind density and a pair of time-based parameters. Both models accurately predict Pc3 intensity from unseen solar wind data. It is observed that Pc3 activity ceases when the density in the solar wind is very low, even while other conditions are favourable for the generation and propagation of ULF waves. The influence that solar wind density has on Pc3 activity is studied by analysing six years of solar wind and Pc3 measurements at one minute resolution. It is suggested that the pause in Pc3 activity occurs due to two reasons: Firstly, the ULF waves that are generated in the region upstream of the bow shock does not grow efficiently if the solar wind density is very low; and secondly, waves that are generated cannot be convected into the magnetosphere because of the low Mach number of the solar wind plasma due to the decreased density.
- Full Text:
- Date Issued: 2012
- Authors: Lotz, Stefanus Ignatius
- Date: 2012
- Subjects: Solar wind -- Research Solar activity -- Research Stellar oscillations -- Research , Magnetospheric radio wave propagation , Interplanetary magnetic fields
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5464 , http://hdl.handle.net/10962/d1005249
- Description: Geomagnetic pulsations are ultra-low frequency (ULF) oscillations of the geomagnetic field that have been observed in the magnetosphere and on the Earth since the 1800’s. In the 1960’s in situ observations of the solar wind suggested that the source of pulsation activity must lie beyond the magnetosphere. In this work the influence of several solar wind plasma and interplanetary magnetic field (IMF) parameters on Pc3 pulsations are studied. Pc3 pulsations are a class of geomagnetic pulsations with frequency ranging between 22 and 100 mHz. A large dataset of solar wind and pulsation measurements is employed to develop two empirical models capable of predicting the Pc3 index (an indication of Pc3 intensity) at one hour and five minute time resolution, respectively. The models are based on artificial neural networks, due to their ability to model highly non-linear interactions between dependent and independent variables. A robust, iterative process is followed to find and rank the set of solar wind input parameters that optimally predict Pc3 activity. According to the parameter selection process the input parameters to the low resolution model (1 hour data) are, in order of importance, solar wind speed, a pair of time-based parameters, dynamic solar wind pressure, and the IMF orientation with respect to the Sun-Earth line (i.e. the cone angle). Input parameters to the high resolution model (5 minute data) are solar wind speed, cone angle, solar wind density and a pair of time-based parameters. Both models accurately predict Pc3 intensity from unseen solar wind data. It is observed that Pc3 activity ceases when the density in the solar wind is very low, even while other conditions are favourable for the generation and propagation of ULF waves. The influence that solar wind density has on Pc3 activity is studied by analysing six years of solar wind and Pc3 measurements at one minute resolution. It is suggested that the pause in Pc3 activity occurs due to two reasons: Firstly, the ULF waves that are generated in the region upstream of the bow shock does not grow efficiently if the solar wind density is very low; and secondly, waves that are generated cannot be convected into the magnetosphere because of the low Mach number of the solar wind plasma due to the decreased density.
- Full Text:
- Date Issued: 2012
Enhanced sensor-based interaction techniques for mobile map-based applications
- Authors: Van Tonder, Bradley Paul
- Date: 2012
- Subjects: Cartography , User interfaces (Computer systems) -- Design , Digital mapping
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10483 , http://hdl.handle.net/10948/d1012995
- Description: Mobile phones are increasingly being equipped with a wide range of sensors which enable a variety of interaction techniques. Sensor-based interaction techniques are particularly promising for domains such as map-based applications, where the user is required to interact with a large information space on the small screen of a mobile phone. Traditional interaction techniques have several shortcomings for interacting with mobile map-based applications. Keypad interaction offers limited control over panning speed and direction. Touch-screen interaction is often a two-handed form of interaction and results in the display being occluded during interaction. Sensor-based interaction provides the potential to address many of these shortcomings, but currently suffers from several limitations. The aim of this research was to propose enhancements to address the shortcomings of sensor-based interaction, with a particular focus on tilt interaction. A comparative study between tilt and keypad interaction was conducted using a prototype mobile map-based application. This user study was conducted in order to identify shortcomings and opportunities for improving tilt interaction techniques in this domain. Several shortcomings, including controllability, mental demand and practicality concerns were highlighted. Several enhanced tilt interaction techniques were proposed to address these shortcomings. These techniques were the use of visual and vibrotactile feedback, attractors, gesture zooming, sensitivity adaptation and dwell-time selection. The results of a comparative user study showed that the proposed techniques achieved several improvements in terms of the problem areas identified earlier. The use of sensor fusion for tilt interaction was compared to an accelerometer-only approach which has been widely applied in existing research. This evaluation was motivated by advances in mobile sensor technology which have led to the widespread adoption of digital compass and gyroscope sensors. The results of a comparative user study between sensor fusion and accelerometer-only implementations of tilt interaction showed several advantages for the use of sensor fusion, particularly in a walking context of use. Modifications to sensitivity adaptation and the use of tilt to perform zooming were also investigated. These modifications were designed to address controllability shortcomings identified in earlier experimental work. The results of a comparison between tilt zooming and Summary gesture zooming indicated that tilt zooming offered better results, both in terms of performance and subjective user ratings. Modifications to the original sensitivity adaptation algorithm were only partly successful. Greater accuracy improvements were achieved for walking tasks, but the use of dynamic dampening factors was found to be confusing. The results of this research were used to propose a framework for mobile tilt interaction. This framework provides an overview of the tilt interaction process and highlights how the enhanced techniques proposed in this research can be integrated into the design of tilt interaction techniques. The framework also proposes an application architecture which was implemented as an Application Programming Interface (API). This API was successfully used in the development of two prototype mobile applications incorporating tilt interaction.
- Full Text:
- Date Issued: 2012
- Authors: Van Tonder, Bradley Paul
- Date: 2012
- Subjects: Cartography , User interfaces (Computer systems) -- Design , Digital mapping
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10483 , http://hdl.handle.net/10948/d1012995
- Description: Mobile phones are increasingly being equipped with a wide range of sensors which enable a variety of interaction techniques. Sensor-based interaction techniques are particularly promising for domains such as map-based applications, where the user is required to interact with a large information space on the small screen of a mobile phone. Traditional interaction techniques have several shortcomings for interacting with mobile map-based applications. Keypad interaction offers limited control over panning speed and direction. Touch-screen interaction is often a two-handed form of interaction and results in the display being occluded during interaction. Sensor-based interaction provides the potential to address many of these shortcomings, but currently suffers from several limitations. The aim of this research was to propose enhancements to address the shortcomings of sensor-based interaction, with a particular focus on tilt interaction. A comparative study between tilt and keypad interaction was conducted using a prototype mobile map-based application. This user study was conducted in order to identify shortcomings and opportunities for improving tilt interaction techniques in this domain. Several shortcomings, including controllability, mental demand and practicality concerns were highlighted. Several enhanced tilt interaction techniques were proposed to address these shortcomings. These techniques were the use of visual and vibrotactile feedback, attractors, gesture zooming, sensitivity adaptation and dwell-time selection. The results of a comparative user study showed that the proposed techniques achieved several improvements in terms of the problem areas identified earlier. The use of sensor fusion for tilt interaction was compared to an accelerometer-only approach which has been widely applied in existing research. This evaluation was motivated by advances in mobile sensor technology which have led to the widespread adoption of digital compass and gyroscope sensors. The results of a comparative user study between sensor fusion and accelerometer-only implementations of tilt interaction showed several advantages for the use of sensor fusion, particularly in a walking context of use. Modifications to sensitivity adaptation and the use of tilt to perform zooming were also investigated. These modifications were designed to address controllability shortcomings identified in earlier experimental work. The results of a comparison between tilt zooming and Summary gesture zooming indicated that tilt zooming offered better results, both in terms of performance and subjective user ratings. Modifications to the original sensitivity adaptation algorithm were only partly successful. Greater accuracy improvements were achieved for walking tasks, but the use of dynamic dampening factors was found to be confusing. The results of this research were used to propose a framework for mobile tilt interaction. This framework provides an overview of the tilt interaction process and highlights how the enhanced techniques proposed in this research can be integrated into the design of tilt interaction techniques. The framework also proposes an application architecture which was implemented as an Application Programming Interface (API). This API was successfully used in the development of two prototype mobile applications incorporating tilt interaction.
- Full Text:
- Date Issued: 2012
Enlarging the place of human rights and development in international trade regulation: an evaluation of the problems and prospects of incorporating a social clause in the legal framework of the World Trade Organization
- Authors: Warikandwa, Tapiwa Victor
- Date: 2012
- Subjects: Social Clause -- Development -- International Trade Regulation -- Human Rights -- World Trade Organization
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: vital:11120 , http://hdl.handle.net/10353/d1015224
- Description: An agreement on the inclusion of a social clause in the World Trade Organization‟s (WTO) multilateral trade agreements largely depends on reassuring objecting member states that such inclusion will contribute to an improved recognition of core labour standards in trade, without altering the competitive advantage of one trading partner over another. Reassurance must be given to the effect that incorporating a social clause in the WTO legal framework would not be used as a trade restricting mechanism which might have direct, negative effects on the development of countries worldwide. Such an argument may not be won easily from a legal and economic perspective. There is an omnipresent conflict at the international level between the basic values underlying multilateral trade agreements and principles governing the protection of core labour standards. On the one hand, supporting the stance of free trade is the fundamental force of profit maximization while on the other hand, and in direct opposition to this market driven value system, are human rights-based calls for recognising core labour standards in employment matters related to trade. Increased international trade is a powerful tool for tackling poverty and social misery worldwide. It could thus be important to adopt a legal framework in the multilateral trade system to harness potential opportunities a trade-labour linkage could provide. In that case, the legal questions of whether or not there should be a tradeoff between the right to trade and compliance with core labour standards and whether a social clause in the WTO would achieve this purpose had to be addressed. However, without a compatible underpinning legal framework of universally accepted trade-labour standards, incorporating a social clause in the WTO would be a misplaced legal objective which is unachievable as it could lead to a conflict between the WTO and the International Labour Organisation (ILO) and at most could create a legal fiction whose results may not be positively measurable. Setting two international legal norms at conflict with each other is systematically studied as a conflict in which the values of the global market economy are in a supposed confrontation with those protecting core labour standards as human rights. Therefore, this study undertook a contemporary legal analysis of the possibilities and challenges of incorporating a social clause in the WTO for purposes of entrenching the protection of core labour standards. It put forward arguments and tentative proposals for a trade-labour linkage legal framework which could dispel calls for excluding a social clause in the WTO.
- Full Text:
- Date Issued: 2012
- Authors: Warikandwa, Tapiwa Victor
- Date: 2012
- Subjects: Social Clause -- Development -- International Trade Regulation -- Human Rights -- World Trade Organization
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: vital:11120 , http://hdl.handle.net/10353/d1015224
- Description: An agreement on the inclusion of a social clause in the World Trade Organization‟s (WTO) multilateral trade agreements largely depends on reassuring objecting member states that such inclusion will contribute to an improved recognition of core labour standards in trade, without altering the competitive advantage of one trading partner over another. Reassurance must be given to the effect that incorporating a social clause in the WTO legal framework would not be used as a trade restricting mechanism which might have direct, negative effects on the development of countries worldwide. Such an argument may not be won easily from a legal and economic perspective. There is an omnipresent conflict at the international level between the basic values underlying multilateral trade agreements and principles governing the protection of core labour standards. On the one hand, supporting the stance of free trade is the fundamental force of profit maximization while on the other hand, and in direct opposition to this market driven value system, are human rights-based calls for recognising core labour standards in employment matters related to trade. Increased international trade is a powerful tool for tackling poverty and social misery worldwide. It could thus be important to adopt a legal framework in the multilateral trade system to harness potential opportunities a trade-labour linkage could provide. In that case, the legal questions of whether or not there should be a tradeoff between the right to trade and compliance with core labour standards and whether a social clause in the WTO would achieve this purpose had to be addressed. However, without a compatible underpinning legal framework of universally accepted trade-labour standards, incorporating a social clause in the WTO would be a misplaced legal objective which is unachievable as it could lead to a conflict between the WTO and the International Labour Organisation (ILO) and at most could create a legal fiction whose results may not be positively measurable. Setting two international legal norms at conflict with each other is systematically studied as a conflict in which the values of the global market economy are in a supposed confrontation with those protecting core labour standards as human rights. Therefore, this study undertook a contemporary legal analysis of the possibilities and challenges of incorporating a social clause in the WTO for purposes of entrenching the protection of core labour standards. It put forward arguments and tentative proposals for a trade-labour linkage legal framework which could dispel calls for excluding a social clause in the WTO.
- Full Text:
- Date Issued: 2012
Evaluation of international aid in Nelson Mandela Bay and Buffalo City Metropolitan Municipalities in the Eastern Cape Province of South Africa
- Authors: Lwanga-Iga, Ivan
- Date: 2012
- Subjects: United Nations -- Economic assistance , Economic assistance -- South Africa -- Eastern Cape , International cooperation -- Municipal government -- South Africa -- Eastern Cape , Human services -- South Africa -- Eastern Cape , Eastern Cape -- South Africa -- Economic policy , Eastern Cape -- South Africa -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD (Social Science Dev)
- Identifier: vital:11437 , http://hdl.handle.net/10353/d1007219 , United Nations -- Economic assistance , Economic assistance -- South Africa -- Eastern Cape , International cooperation -- Municipal government -- South Africa -- Eastern Cape , Human services -- South Africa -- Eastern Cape , Eastern Cape -- South Africa -- Economic policy , Eastern Cape -- South Africa -- Economic conditions
- Description: International Aid or Official Development Assistance (ODA), especially its implementation and effectiveness, has long been and continues to be a vigorously contested matter amongst the stakeholders in the development arena. The objective of this study is to evaluate the effectiveness of ODA in two municipalities in the Eastern Cape – Buffalo City and Nelson Mandela Metropolitan Municipalities – during the period 2005–2010. This period coincided with the introduction of the Paris Declaration (PD), an intervention intended to improve the ODA or Aid landscape globally. This was also the period during which the so-called service delivery protests in almost all municipalities in South Africa escalated. A diversified methodology including both quantitative and qualitative approaches was used in this study while adhering to the evaluation framework of the Paris Declaration as recommended by the Organisation for Economic Cooperation and Development (OECD). This framework put special focus on the five principles of ownership, alignment, harmonisation, managing for results and mutual accountability. Of particular significance in this study is the special attention paid to the actual beneficiaries on the ground, namely the communities, which is contrary to most existing Paris Declaration evaluations. The research findings suggested that there had been no conscious efforts to implement the Paris Declaration in the two municipalities that were investigated. Furthermore, the prevailing weaknesses in governance, coupled with both administrative and operational paralysis in these two institutions, provided for less than fertile ground for this intervention to thrive.The findings also highlighted that ODA programmes were very poorly known by most stakeholders, especially the communities who were supposed to benefit directly from this assistance. These results also underscored the partisan nature of ODA and how it influenced the perceptions of the various key players. The success and future of ODA programmes in South Africa, particularly in municipalities, will largely rely on “Active Citizenry”. Although ODA’s contribution to South Africa seems negligible in monetary terms, its significance lies among others in the innovations, piloting, risk mitigation, catalytic initiatives and capacity development it introduces or generates and which need to be correctly exploited, implemented and maximised. ODA in South Africa should therefore focus at the local level, the municipalities, which represent the interface between the citizens and the state. To ensure that the ensuing innovations are optimally cascaded down in an organised and effective manner to where they are mostly needed, ODA should preferably operate at the strategic level in municipalities. This would in turn assist in counteracting the current high levels of poverty and inequality in the country. Study findings further suggest that South Africa should cease its current ambivalence regarding ODA and refrain from the so-called “Triangular” ODA in support of the rest of Africa. The demands in it’s own back yard are steadily mounting. This is clearly reflected by the continuous service delivery protests and instability in several municipalities in South Africa.
- Full Text:
- Date Issued: 2012
- Authors: Lwanga-Iga, Ivan
- Date: 2012
- Subjects: United Nations -- Economic assistance , Economic assistance -- South Africa -- Eastern Cape , International cooperation -- Municipal government -- South Africa -- Eastern Cape , Human services -- South Africa -- Eastern Cape , Eastern Cape -- South Africa -- Economic policy , Eastern Cape -- South Africa -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD (Social Science Dev)
- Identifier: vital:11437 , http://hdl.handle.net/10353/d1007219 , United Nations -- Economic assistance , Economic assistance -- South Africa -- Eastern Cape , International cooperation -- Municipal government -- South Africa -- Eastern Cape , Human services -- South Africa -- Eastern Cape , Eastern Cape -- South Africa -- Economic policy , Eastern Cape -- South Africa -- Economic conditions
- Description: International Aid or Official Development Assistance (ODA), especially its implementation and effectiveness, has long been and continues to be a vigorously contested matter amongst the stakeholders in the development arena. The objective of this study is to evaluate the effectiveness of ODA in two municipalities in the Eastern Cape – Buffalo City and Nelson Mandela Metropolitan Municipalities – during the period 2005–2010. This period coincided with the introduction of the Paris Declaration (PD), an intervention intended to improve the ODA or Aid landscape globally. This was also the period during which the so-called service delivery protests in almost all municipalities in South Africa escalated. A diversified methodology including both quantitative and qualitative approaches was used in this study while adhering to the evaluation framework of the Paris Declaration as recommended by the Organisation for Economic Cooperation and Development (OECD). This framework put special focus on the five principles of ownership, alignment, harmonisation, managing for results and mutual accountability. Of particular significance in this study is the special attention paid to the actual beneficiaries on the ground, namely the communities, which is contrary to most existing Paris Declaration evaluations. The research findings suggested that there had been no conscious efforts to implement the Paris Declaration in the two municipalities that were investigated. Furthermore, the prevailing weaknesses in governance, coupled with both administrative and operational paralysis in these two institutions, provided for less than fertile ground for this intervention to thrive.The findings also highlighted that ODA programmes were very poorly known by most stakeholders, especially the communities who were supposed to benefit directly from this assistance. These results also underscored the partisan nature of ODA and how it influenced the perceptions of the various key players. The success and future of ODA programmes in South Africa, particularly in municipalities, will largely rely on “Active Citizenry”. Although ODA’s contribution to South Africa seems negligible in monetary terms, its significance lies among others in the innovations, piloting, risk mitigation, catalytic initiatives and capacity development it introduces or generates and which need to be correctly exploited, implemented and maximised. ODA in South Africa should therefore focus at the local level, the municipalities, which represent the interface between the citizens and the state. To ensure that the ensuing innovations are optimally cascaded down in an organised and effective manner to where they are mostly needed, ODA should preferably operate at the strategic level in municipalities. This would in turn assist in counteracting the current high levels of poverty and inequality in the country. Study findings further suggest that South Africa should cease its current ambivalence regarding ODA and refrain from the so-called “Triangular” ODA in support of the rest of Africa. The demands in it’s own back yard are steadily mounting. This is clearly reflected by the continuous service delivery protests and instability in several municipalities in South Africa.
- Full Text:
- Date Issued: 2012
Exploiting the adaptability of recent information and communication technology to improve the site management process
- Ozumba, Aghaegbuna Obinna Uche
- Authors: Ozumba, Aghaegbuna Obinna Uche
- Date: 2012
- Subjects: Construction industry -- Information technology , Construction industry -- Materials management , Information technology -- Management.
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9705 , http://hdl.handle.net/10948/d1019811
- Description: Construction is a big role player in every economy, and the Site Management Process (SMP) occupies a strategic position in the construction process. Despite existence of appreciable research, technology diffusion in the construction industry is slow. Information and Communication Technology (ICT) implementation processes and products have not adequately and beneficially exploited ICT for improvement of the SMP. This is especially true in developing countries. Without increase in utilisation of ICT, potential benefits for the SMP remain untapped. The aim of the thesis was to ascertain the levels of utilisation of recent ICT developments for the SMP, and thereby gauge the benefits or lack thereof. The theoretical concept of the research is based on the technology transfer sub-concept of adaptation. A fundamentally positivistic view, with principles of objectivist approach was used for the enquiry. The approach included an extensive literature review, and a multi-stage investigation strategy, set in South Africa. Theory reviewed was in the main disciplines of construction science and technology, computer science and technology, and management science. Investigations involved case studies of construction sites, a global ICT survey, a national practitioner survey, and analysis of ICT products. Findings from literature assert the appreciable potential utility in recent ICT, thereby substantiating the adaptability of recent ICT. In addition ICT adoption in the SMP is inadequate and inexpedient, falling short of potential benefits for construction, both generally and in the local context. Furthermore there are challenges to ICT adoption, which could vary according to context. Field research results also point to underutilisation of innovations located in recent ICT. The main challenges in this regard include inadequate knowledge of potential utility of recent ICT, and lack of relevant support and effective approaches to technology integration, in the SMP. Moreover exploitation of the adaptability of recent ICT in the local SMP does not go beyond basic adoption. As such most diffusion occurs only for items requiring an adaptation of usage context or area of application. The results strongly indicate minimal innovativeness in this regard. Frameworks for possible adaptations of existing technologies were also derived, while propositions are made for approaches to improve the utility of recent ICT in the SMP. Through a customised approach, the thesis establishes foundational understanding towards a generic framework for adapting potential utility in ICT to uses in construction, especially in the SMP. Thus the research contributes strategic information to the fledgling CICT body of knowledge, especially in the local context.
- Full Text:
- Date Issued: 2012
- Authors: Ozumba, Aghaegbuna Obinna Uche
- Date: 2012
- Subjects: Construction industry -- Information technology , Construction industry -- Materials management , Information technology -- Management.
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9705 , http://hdl.handle.net/10948/d1019811
- Description: Construction is a big role player in every economy, and the Site Management Process (SMP) occupies a strategic position in the construction process. Despite existence of appreciable research, technology diffusion in the construction industry is slow. Information and Communication Technology (ICT) implementation processes and products have not adequately and beneficially exploited ICT for improvement of the SMP. This is especially true in developing countries. Without increase in utilisation of ICT, potential benefits for the SMP remain untapped. The aim of the thesis was to ascertain the levels of utilisation of recent ICT developments for the SMP, and thereby gauge the benefits or lack thereof. The theoretical concept of the research is based on the technology transfer sub-concept of adaptation. A fundamentally positivistic view, with principles of objectivist approach was used for the enquiry. The approach included an extensive literature review, and a multi-stage investigation strategy, set in South Africa. Theory reviewed was in the main disciplines of construction science and technology, computer science and technology, and management science. Investigations involved case studies of construction sites, a global ICT survey, a national practitioner survey, and analysis of ICT products. Findings from literature assert the appreciable potential utility in recent ICT, thereby substantiating the adaptability of recent ICT. In addition ICT adoption in the SMP is inadequate and inexpedient, falling short of potential benefits for construction, both generally and in the local context. Furthermore there are challenges to ICT adoption, which could vary according to context. Field research results also point to underutilisation of innovations located in recent ICT. The main challenges in this regard include inadequate knowledge of potential utility of recent ICT, and lack of relevant support and effective approaches to technology integration, in the SMP. Moreover exploitation of the adaptability of recent ICT in the local SMP does not go beyond basic adoption. As such most diffusion occurs only for items requiring an adaptation of usage context or area of application. The results strongly indicate minimal innovativeness in this regard. Frameworks for possible adaptations of existing technologies were also derived, while propositions are made for approaches to improve the utility of recent ICT in the SMP. Through a customised approach, the thesis establishes foundational understanding towards a generic framework for adapting potential utility in ICT to uses in construction, especially in the SMP. Thus the research contributes strategic information to the fledgling CICT body of knowledge, especially in the local context.
- Full Text:
- Date Issued: 2012
Exploring the linkages between biodiversity conservation and ecotourism in protected areas
- Authors: Maciejewski, Kristine
- Date: 2012
- Subjects: Biodiversity conservation , Ecotourism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10709 , http://hdl.handle.net/10948/d1011033 , Biodiversity conservation , Ecotourism
- Description: The prospect of using ecotourism to add value to conservation initiatives has frequently been stated. However, there is a general lack of information on the costs and benefits of biodiversity and its management, and how this can be influenced by the ecotourism industry. This study seeks to explore the value of biodiversity from the perspective of ecotourism in a hierarchical series of studies that move from the biome-level perspective down to the value of juveniles in ecotourism. Ecotourism plays a significant role in the establishment and management of Private Protected Areas (PPAs) and hence the opportunity to be added to the conservation estate. The financial opportunity to be found in ‘big five’ areas had led to an uneven biome coverage of PPAs which has resulted in the over-representation of certain areas and a skewed contribution towards national conservation targets. The landscape-use of PPAs have indicated that ecotourism operators are largely driven to achieve successful game-viewing sightings which has influenced management and affected the landscape use of PPAs, the stocking rate of species, the introduction of extralimital species, and management of flagship species. These management decisions are based on anecdotal sources and have been made at the expense of biodiversity and therefore apparent conflict exists between ecotourism and conservation objectives. This is based on lack of information: ecotourism operators, despite the large area they protect, have not realised their potential to contribute to conservation. It is therefore important to develop policy and incentives to motivate the establishment of PPAs in areas of high conservation significance in order to contribute to national conservation targets. Ecotourism should be used as a solution to provide important insights into tourist preferences which contribute to the larger debate of how to establish a balance between managing animal populations to ensure tourist satisfaction while supporting conservation. To ensure sustainability of PPAs, it is strongly recommended to manage PPAs more intensively with regards to PPA size, species stocking rates and landscape use. The presence of juveniles at an animal sighting significantly contributes to tourist satisfaction which suggests that the loss of juveniles may reduce the attraction. This is used to provide recommendations that using contraception to control elephant population numbers should be applied with caution as a management tool as it may be counterproductive by negatively impacting ecotourism. The findings from this study not only contribute to the conservation of biodiversity through the use of ecotourism, but will also ensure sustainability of the ecotourism industry and build capacity for sustainable living.
- Full Text:
- Date Issued: 2012
- Authors: Maciejewski, Kristine
- Date: 2012
- Subjects: Biodiversity conservation , Ecotourism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10709 , http://hdl.handle.net/10948/d1011033 , Biodiversity conservation , Ecotourism
- Description: The prospect of using ecotourism to add value to conservation initiatives has frequently been stated. However, there is a general lack of information on the costs and benefits of biodiversity and its management, and how this can be influenced by the ecotourism industry. This study seeks to explore the value of biodiversity from the perspective of ecotourism in a hierarchical series of studies that move from the biome-level perspective down to the value of juveniles in ecotourism. Ecotourism plays a significant role in the establishment and management of Private Protected Areas (PPAs) and hence the opportunity to be added to the conservation estate. The financial opportunity to be found in ‘big five’ areas had led to an uneven biome coverage of PPAs which has resulted in the over-representation of certain areas and a skewed contribution towards national conservation targets. The landscape-use of PPAs have indicated that ecotourism operators are largely driven to achieve successful game-viewing sightings which has influenced management and affected the landscape use of PPAs, the stocking rate of species, the introduction of extralimital species, and management of flagship species. These management decisions are based on anecdotal sources and have been made at the expense of biodiversity and therefore apparent conflict exists between ecotourism and conservation objectives. This is based on lack of information: ecotourism operators, despite the large area they protect, have not realised their potential to contribute to conservation. It is therefore important to develop policy and incentives to motivate the establishment of PPAs in areas of high conservation significance in order to contribute to national conservation targets. Ecotourism should be used as a solution to provide important insights into tourist preferences which contribute to the larger debate of how to establish a balance between managing animal populations to ensure tourist satisfaction while supporting conservation. To ensure sustainability of PPAs, it is strongly recommended to manage PPAs more intensively with regards to PPA size, species stocking rates and landscape use. The presence of juveniles at an animal sighting significantly contributes to tourist satisfaction which suggests that the loss of juveniles may reduce the attraction. This is used to provide recommendations that using contraception to control elephant population numbers should be applied with caution as a management tool as it may be counterproductive by negatively impacting ecotourism. The findings from this study not only contribute to the conservation of biodiversity through the use of ecotourism, but will also ensure sustainability of the ecotourism industry and build capacity for sustainable living.
- Full Text:
- Date Issued: 2012
Exploring the use of folktales to enhance the resilince of children orphaned and rendered vulnerable
- Authors: Mayaba, Nokhanyo Nomakhwezi
- Date: 2012
- Subjects: Narrative therapy , Resilience (Personality trait) in children -- South Africa , Loss (Psychology) in children , Children of AIDS patients -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9513 , http://hdl.handle.net/10948/2776 , Narrative therapy , Resilience (Personality trait) in children -- South Africa , Loss (Psychology) in children , Children of AIDS patients -- South Africa
- Description: The recent increase in the number of children orphaned and rendered vulnerable by HIV and AIDS in South Africa has placed an added burden on schools as sites of care and support. Education policies mandate schools to develop strategies to support such children, but this is no easy task in contexts where teachers are already struggling to fulfill instructional requirements. Literature reveals that teachers in under-resourced schools, where the problem is more severely experienced regard this increased pastoral role as an added responsibility that they do not feel competent to execute. Since there is unlikely to be any significant improvement in the circumstances of these children in the near future, there is a need to discover creative ways to address this problem. I was led to ask how teachers could support children to better cope in the face of adversity in a way that could be easily integrated into the academic curriculum, so as to minimise the perceived burden of providing care and support. Based on my knowledge of the value of bibliotherapy in promoting resilient coping in individuals, I was interested to see if folktales could be used in a similar way with groups of children. Working from an asset-based perspective, and proceeding from a transformative and participatory epistemology, I adopted an action research design to explore the potential of traditional folktales to enhance positive coping responses in children orphaned and rendered vulnerable by HIV and AIDS. My choice of traditional folktales was influenced by the importance that resilience theory attaches to cultural variables in the resilience process. The participants were isiXhosa speaking children who were orphaned and rendered vulnerable by HIV and AIDS (OVC) between the ages of nine and fourteen years (n=30) in Cycle One who lived in a children‟s home or with foster parents. In Cycle Two, the study was conducted in a school setting with thirty (n=30) participants. I conducted two cycles of reflective action research enquiry to ascertain how folktales could be used to enable teachers to meet both pastoral and academic requirements. In the first cycle, I used a pre-post time series design to explore if merely telling the stories would enhance the resilience of the children. Although this use of the stories was teacher-centred, I knew that it would be an easy and time-saving way for teachers to provide support, if it proved to be effective in enhancing resilience. Drawings and accompanying explanations were used to generate data pre-and post-intervention. The thematic analysis of the data revealed that, post-intervention, there appeared to be an increase in two resilience-enhancing indicators: the children appeared to have a more positive sense of self and improved positive relations with peers/friends. Critical reflection on the process also revealed ethical and methodological concerns and problems when working with vulnerable children. The findings from this cycle informed my second cycle, in which I adopted a more participatory approach to engage the children in making meaning of the stories and explore how they related to their own lives. I used participatory arts based methods such as drawings, collages, drama and more usual qualitative strategies, such as focus group discussion and observation, to generate data. The findings from this cycle suggest that using such strategies will equip teachers with tools to enhance the resilience of OVC in a way that also promotes the attainment of instructional outcomes. This study has contributed important theoretical, methodological and pedagogical insights. Theoretically, this study has contributed to the social ecological perspective of resilience by confirming that cultural resources, such as indigenous African stories (folktales) can enhance the resilience of vulnerable children. Lessons learnt from this study had a methodological contribution to the ethics of working with children and the use of culturally appropriate resources in the field, which were folktales. This study has also contributed to the meaning making implications of using folktales, which can aid the pedagogical strategies that teachers use. Although this study was meant to be small- scale research and was not intended to be generalisable, the findings do suggest that teachers could have a resource that is time efficient, effective and could assist them to reach both their pastoral and academic goals.
- Full Text:
- Date Issued: 2012
Exploring the use of folktales to enhance the resilince of children orphaned and rendered vulnerable
- Authors: Mayaba, Nokhanyo Nomakhwezi
- Date: 2012
- Subjects: Narrative therapy , Resilience (Personality trait) in children -- South Africa , Loss (Psychology) in children , Children of AIDS patients -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9513 , http://hdl.handle.net/10948/2776 , Narrative therapy , Resilience (Personality trait) in children -- South Africa , Loss (Psychology) in children , Children of AIDS patients -- South Africa
- Description: The recent increase in the number of children orphaned and rendered vulnerable by HIV and AIDS in South Africa has placed an added burden on schools as sites of care and support. Education policies mandate schools to develop strategies to support such children, but this is no easy task in contexts where teachers are already struggling to fulfill instructional requirements. Literature reveals that teachers in under-resourced schools, where the problem is more severely experienced regard this increased pastoral role as an added responsibility that they do not feel competent to execute. Since there is unlikely to be any significant improvement in the circumstances of these children in the near future, there is a need to discover creative ways to address this problem. I was led to ask how teachers could support children to better cope in the face of adversity in a way that could be easily integrated into the academic curriculum, so as to minimise the perceived burden of providing care and support. Based on my knowledge of the value of bibliotherapy in promoting resilient coping in individuals, I was interested to see if folktales could be used in a similar way with groups of children. Working from an asset-based perspective, and proceeding from a transformative and participatory epistemology, I adopted an action research design to explore the potential of traditional folktales to enhance positive coping responses in children orphaned and rendered vulnerable by HIV and AIDS. My choice of traditional folktales was influenced by the importance that resilience theory attaches to cultural variables in the resilience process. The participants were isiXhosa speaking children who were orphaned and rendered vulnerable by HIV and AIDS (OVC) between the ages of nine and fourteen years (n=30) in Cycle One who lived in a children‟s home or with foster parents. In Cycle Two, the study was conducted in a school setting with thirty (n=30) participants. I conducted two cycles of reflective action research enquiry to ascertain how folktales could be used to enable teachers to meet both pastoral and academic requirements. In the first cycle, I used a pre-post time series design to explore if merely telling the stories would enhance the resilience of the children. Although this use of the stories was teacher-centred, I knew that it would be an easy and time-saving way for teachers to provide support, if it proved to be effective in enhancing resilience. Drawings and accompanying explanations were used to generate data pre-and post-intervention. The thematic analysis of the data revealed that, post-intervention, there appeared to be an increase in two resilience-enhancing indicators: the children appeared to have a more positive sense of self and improved positive relations with peers/friends. Critical reflection on the process also revealed ethical and methodological concerns and problems when working with vulnerable children. The findings from this cycle informed my second cycle, in which I adopted a more participatory approach to engage the children in making meaning of the stories and explore how they related to their own lives. I used participatory arts based methods such as drawings, collages, drama and more usual qualitative strategies, such as focus group discussion and observation, to generate data. The findings from this cycle suggest that using such strategies will equip teachers with tools to enhance the resilience of OVC in a way that also promotes the attainment of instructional outcomes. This study has contributed important theoretical, methodological and pedagogical insights. Theoretically, this study has contributed to the social ecological perspective of resilience by confirming that cultural resources, such as indigenous African stories (folktales) can enhance the resilience of vulnerable children. Lessons learnt from this study had a methodological contribution to the ethics of working with children and the use of culturally appropriate resources in the field, which were folktales. This study has also contributed to the meaning making implications of using folktales, which can aid the pedagogical strategies that teachers use. Although this study was meant to be small- scale research and was not intended to be generalisable, the findings do suggest that teachers could have a resource that is time efficient, effective and could assist them to reach both their pastoral and academic goals.
- Full Text:
- Date Issued: 2012
Factors affecting the implementation of the National Curriculum Statement in the Mthatha education district
- Gobingca, Berington Zanoxolo
- Authors: Gobingca, Berington Zanoxolo
- Date: 2012
- Subjects: Curriculum planning -- South Africa -- Eastern Cape , Curriculum change -- South Africa , Education -- South Africa -- Curricula
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9442
- Description: The current investigation was conducted in the Mthatha Education District. It sought to investigate factors affecting the implementation of the National Curriculum Statement (NCS) in the Mthatha schools of the Eastern Cape Province in South Africa. Literature reviewed showed that teachers, as the key role players to the implementation of the curriculum in schools, are still experiencing difficulties in implementing the NCS. It is thus important to establish and investigate the factors affecting the implementation of the NCS. The research was both exploratory and explanatory in nature and adopted a mixed method approach. Questionnaires were distributed among 210 teachers who were randomly selected from 363 schools in the Mthatha Education District. Out of 210 teachers who were provided with questionnaires to fill out, it was 148 (70.5 percent) of them who completed and returned the questionnaires. Semi-structured interviews were conducted face-to-face with 10 purposefully selected teachers to collect the data from those who participated by filling out the questionnaires. The researcher analysed the data both quantitatively and qualitatively. The data was presented, analysed and discussed according to themes derived from the main research question and sub-questions. The quantitative data (closed-ended statements) was analysed statistically by means of the Statistical Package for Social Sciences (SPSS). In the case of the qualitative data (open-ended statements in questionnaires and interviews), similar responses were analysed in themes as per the research question and sub-questions for easy interpretation. Note-taking and tape-recording were done during the interview sessions. Qualitative data were transcribed, coded and analysed. The findings which emerged from the study indicated that intermediate-phase teachers experienced difficulties in implementing the NCS. These were attributed to, amongst others, a lack of resources such as learning material and infrastructure, redeployment of teachers, a high learner teacher ratio, inadequate in-service training and support from the DoE. These factors need to be addressed to enhance the implementation of the NCS and to avoid the repetition of those shortcomings in any future envisaged changes to the curriculum such as the implementation of CAPS.
- Full Text:
- Date Issued: 2012
- Authors: Gobingca, Berington Zanoxolo
- Date: 2012
- Subjects: Curriculum planning -- South Africa -- Eastern Cape , Curriculum change -- South Africa , Education -- South Africa -- Curricula
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9442
- Description: The current investigation was conducted in the Mthatha Education District. It sought to investigate factors affecting the implementation of the National Curriculum Statement (NCS) in the Mthatha schools of the Eastern Cape Province in South Africa. Literature reviewed showed that teachers, as the key role players to the implementation of the curriculum in schools, are still experiencing difficulties in implementing the NCS. It is thus important to establish and investigate the factors affecting the implementation of the NCS. The research was both exploratory and explanatory in nature and adopted a mixed method approach. Questionnaires were distributed among 210 teachers who were randomly selected from 363 schools in the Mthatha Education District. Out of 210 teachers who were provided with questionnaires to fill out, it was 148 (70.5 percent) of them who completed and returned the questionnaires. Semi-structured interviews were conducted face-to-face with 10 purposefully selected teachers to collect the data from those who participated by filling out the questionnaires. The researcher analysed the data both quantitatively and qualitatively. The data was presented, analysed and discussed according to themes derived from the main research question and sub-questions. The quantitative data (closed-ended statements) was analysed statistically by means of the Statistical Package for Social Sciences (SPSS). In the case of the qualitative data (open-ended statements in questionnaires and interviews), similar responses were analysed in themes as per the research question and sub-questions for easy interpretation. Note-taking and tape-recording were done during the interview sessions. Qualitative data were transcribed, coded and analysed. The findings which emerged from the study indicated that intermediate-phase teachers experienced difficulties in implementing the NCS. These were attributed to, amongst others, a lack of resources such as learning material and infrastructure, redeployment of teachers, a high learner teacher ratio, inadequate in-service training and support from the DoE. These factors need to be addressed to enhance the implementation of the NCS and to avoid the repetition of those shortcomings in any future envisaged changes to the curriculum such as the implementation of CAPS.
- Full Text:
- Date Issued: 2012
Farm level institutions in emergent communities in post fast track Zimbabwe: case of Mazowe district
- Authors: Chiweshe, Manase Kudzai
- Date: 2012
- Subjects: Land reform -- Zimbabwe -- History -- 21st century Land settlement -- Social aspects -- Zimbabwe Zimbabwe -- Social conditions -- 1980- Zimbabwe -- Economic conditions Zimbabwe -- Politics and government -- 1980-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3308 , http://hdl.handle.net/10962/d1003096
- Description: The thesis seeks to understand how emerging communities borne out of the Fast Track Land Reform Programme in Zimbabwe have been able to ensure social cohesion and social service provision using farm level institutions. The Fast Track Programme brought together people from diverse backgrounds into new communities in the former commercial farming areas. The formation of new communities meant that, often, there were 'stranger households'living next to each other. Since 2000, these people have been involved in various processes aimed at turning clusters of homesteads into functioning communities through farm level institutions. Fast track land reform precipitated economic and political crisis in Zimbabwe characterised by a rapidly devaluating Zimbabwean dollar, enormous inflation and high unemployment figures. This economic crisis has impacted heavily on new farmers who find it increasingly difficult to afford inputs and access loans. They have formed social networks in response to these challenges, taking the form of farm level institutions such as farm committees, irrigation committees and health committees. The study uses case studies from small-scale 'A1 farmers‘ in Mazowe district which is in Mashonaland Central Province. It employs qualitative methodologies to enable a nuanced understanding of associational life in the new communities. Through focus group discussions, in-depth interviews, narratives, key informant interviews and institutional mapping the study outlines the formation, taxonomy, activities, roles, internal dynamics and social organisation of farm level institutions. The study also uses secondary data collected in 2007-08 by the Centre for Rural Development in the newly resettled areas in Mazowe. The major finding of the study is that farmers are organising in novel ways at grassroots levels to meet everyday challenges. These institutional forms however are internally weak, lacking leadership with a clear vision and they appear as if they are transitory in nature. They remain marginalised from national and global processes and isolated from critical connections to policy makers at all levels; thus A1 farmers remain voiceless and unable to have their interests addressed. Farm level institutions are at the forefront of the microeconomics of survival among these rural farmers. They are survivalist in nature and form, and this requires a major shift in focus if they are to be involved in developmental work. The institutions remain fragmented and compete amongst themselves for services from government without uniting as A1 farmers with similar interests and challenges.
- Full Text:
- Date Issued: 2012
Farm level institutions in emergent communities in post fast track Zimbabwe: case of Mazowe district
- Authors: Chiweshe, Manase Kudzai
- Date: 2012
- Subjects: Land reform -- Zimbabwe -- History -- 21st century Land settlement -- Social aspects -- Zimbabwe Zimbabwe -- Social conditions -- 1980- Zimbabwe -- Economic conditions Zimbabwe -- Politics and government -- 1980-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3308 , http://hdl.handle.net/10962/d1003096
- Description: The thesis seeks to understand how emerging communities borne out of the Fast Track Land Reform Programme in Zimbabwe have been able to ensure social cohesion and social service provision using farm level institutions. The Fast Track Programme brought together people from diverse backgrounds into new communities in the former commercial farming areas. The formation of new communities meant that, often, there were 'stranger households'living next to each other. Since 2000, these people have been involved in various processes aimed at turning clusters of homesteads into functioning communities through farm level institutions. Fast track land reform precipitated economic and political crisis in Zimbabwe characterised by a rapidly devaluating Zimbabwean dollar, enormous inflation and high unemployment figures. This economic crisis has impacted heavily on new farmers who find it increasingly difficult to afford inputs and access loans. They have formed social networks in response to these challenges, taking the form of farm level institutions such as farm committees, irrigation committees and health committees. The study uses case studies from small-scale 'A1 farmers‘ in Mazowe district which is in Mashonaland Central Province. It employs qualitative methodologies to enable a nuanced understanding of associational life in the new communities. Through focus group discussions, in-depth interviews, narratives, key informant interviews and institutional mapping the study outlines the formation, taxonomy, activities, roles, internal dynamics and social organisation of farm level institutions. The study also uses secondary data collected in 2007-08 by the Centre for Rural Development in the newly resettled areas in Mazowe. The major finding of the study is that farmers are organising in novel ways at grassroots levels to meet everyday challenges. These institutional forms however are internally weak, lacking leadership with a clear vision and they appear as if they are transitory in nature. They remain marginalised from national and global processes and isolated from critical connections to policy makers at all levels; thus A1 farmers remain voiceless and unable to have their interests addressed. Farm level institutions are at the forefront of the microeconomics of survival among these rural farmers. They are survivalist in nature and form, and this requires a major shift in focus if they are to be involved in developmental work. The institutions remain fragmented and compete amongst themselves for services from government without uniting as A1 farmers with similar interests and challenges.
- Full Text:
- Date Issued: 2012
Fertility decline among Abagusii women : the application of an adapted proximate determinants model
- Authors: Onsongo, Francis Omweri
- Date: 2012
- Subjects: Fertility, Human -- Kenya , Birth control -- Kenya , Women, Gusii -- Social conditions , Women's rights -- Kenya , Gusii (African people) -- Social conditions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10669 , http://hdl.handle.net/10948/d1019924
- Description: The primary objective of this thesis is to account for the fertility decline among Abagusii women in South-western Kenya. The motivation behind the study was based on the fact that the fertility trends associated with this group of people had not been studied before. This is surprising because the Abagusii recorded one of the world's highest total fertility rates of 10.4 in 1979 (Omosa 1994; Osiemo 1986; Oucho 1990), but has also experienced significant fertility decline. The total fertility rate in 2004 stood at 4.7, (Anyara 2009). The analytical framework that is adopted is Stover's (1998) adaptation of the Bongaarts et. al. (1984) Proximate Determinants Model. These determinants such as contraceptive use, post-partum insusceptibility, sexual activity, abortion and sterility represent behavioural and biological variables that affect fertility directly. The manner in which they are employed involves using the index which indicates the extent to which each proximate determinant reduces the fertility of the group in question.
- Full Text:
- Date Issued: 2012
- Authors: Onsongo, Francis Omweri
- Date: 2012
- Subjects: Fertility, Human -- Kenya , Birth control -- Kenya , Women, Gusii -- Social conditions , Women's rights -- Kenya , Gusii (African people) -- Social conditions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10669 , http://hdl.handle.net/10948/d1019924
- Description: The primary objective of this thesis is to account for the fertility decline among Abagusii women in South-western Kenya. The motivation behind the study was based on the fact that the fertility trends associated with this group of people had not been studied before. This is surprising because the Abagusii recorded one of the world's highest total fertility rates of 10.4 in 1979 (Omosa 1994; Osiemo 1986; Oucho 1990), but has also experienced significant fertility decline. The total fertility rate in 2004 stood at 4.7, (Anyara 2009). The analytical framework that is adopted is Stover's (1998) adaptation of the Bongaarts et. al. (1984) Proximate Determinants Model. These determinants such as contraceptive use, post-partum insusceptibility, sexual activity, abortion and sterility represent behavioural and biological variables that affect fertility directly. The manner in which they are employed involves using the index which indicates the extent to which each proximate determinant reduces the fertility of the group in question.
- Full Text:
- Date Issued: 2012
Fire regimes in eastern coastal fynbos: drivers, ecology and management
- Authors: Kraaij, Tineke
- Date: 2012
- Subjects: Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10607 , http://hdl.handle.net/10948/d1008047 , Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Description: Conventional knowledge of fynbos fire ecology is based on the summer-autumn fire regimes of the western Cape Floral Kingdom (CFK) where the climate is Mediterranean. However, the climate in the eastern coastal-CFK is milder and rainfall occurs year-round, with presumed effects on fire regimes. The Garden Route National Park (GRNP) has recently been established in the region, in a landscape where indigenous forests, fire-prone fynbos shrublands and fire-sensitive plantations of invasive alien trees are interspersed. The park faces considerable challenges related to the management of fire, including significant pressure from the adjacent plantation industry to reduce wildfire hazard by burning fynbos at short intervals, and high levels of invasion by alien trees (largely Pinus species originating from plantations). This study sought to improve understanding of fire regimes in eastern coastal fynbos shrublands, and to provide guidelines for ecologically sound management of fire in the area. My approach entailed (i) an assessment of the context within which fire management was practiced during the past century; (ii) characterisation of the recent fire history and fire regime (1900–2010); (iii) characterisation of the seasonality of fire weather and lightning; (iv) estimation of minimum fire return intervals (FRIs) from juvenile periods and post-fire recruitment success of overstorey proteoids (non-sprouting, slow-maturing, serotinous Proteaceae); and (v) determination of the ecologically appropriate fire season from post-fire recruitment seasonality of proteoids. I established that historically, plantation protection enjoyed priority over fynbos conservation in the area that is now the GRNP. Fynbos close to plantations has most likely been compromised by frequent and low-intensity burning in the past, as well as by invasion by alien trees. In terms of area burnt (1900–2010), natural (lightning-ignited) fires dominated the fire regime, particularly in the east, whereas prescribed burning was relatively unimportant. Typical fire return intervals (FRIs; 8–26 years; 1980–2010) were comparable to those in other fynbos protected areas and appeared to be shorter in the eastern Tsitsikamma than in the western Outeniqua halves of the study area. Proteaceae juvenile periods (4–9 years) and post-fire recruitment success (following fires in ≥7 year-old vegetation) suggested that for biodiversity conservation purposes, FRIs should be no less than nine years in moist, productive fynbos. Increases in the total area burnt annually (since 1980) were correlated with long-term increases in average fire danger weather, suggesting that fire regime changes may be related to global change. Collectively, findings on the seasonality of actual fires and the seasonality of fire danger weather, lightning, and post-fire proteoid recruitment suggested that fires in eastern coastal fynbos are not limited to any particular season, and for this reason managers do not need to be concerned if fires occur in any season. The ecological requirements for higher fire intensity may nonetheless be constrained by a need for safety. I articulated these findings into ecological thresholds pertaining to the different elements of the fire regime in eastern coastal fynbos, to guide adaptive management of fire in the Garden Route National Park. I also recommended a fire management strategy for the park to address the aforementioned operational considerations within the constraints posed by ecological thresholds. Finally, I highlighted further research and monitoring needs.
- Full Text:
- Date Issued: 2012
- Authors: Kraaij, Tineke
- Date: 2012
- Subjects: Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10607 , http://hdl.handle.net/10948/d1008047 , Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Description: Conventional knowledge of fynbos fire ecology is based on the summer-autumn fire regimes of the western Cape Floral Kingdom (CFK) where the climate is Mediterranean. However, the climate in the eastern coastal-CFK is milder and rainfall occurs year-round, with presumed effects on fire regimes. The Garden Route National Park (GRNP) has recently been established in the region, in a landscape where indigenous forests, fire-prone fynbos shrublands and fire-sensitive plantations of invasive alien trees are interspersed. The park faces considerable challenges related to the management of fire, including significant pressure from the adjacent plantation industry to reduce wildfire hazard by burning fynbos at short intervals, and high levels of invasion by alien trees (largely Pinus species originating from plantations). This study sought to improve understanding of fire regimes in eastern coastal fynbos shrublands, and to provide guidelines for ecologically sound management of fire in the area. My approach entailed (i) an assessment of the context within which fire management was practiced during the past century; (ii) characterisation of the recent fire history and fire regime (1900–2010); (iii) characterisation of the seasonality of fire weather and lightning; (iv) estimation of minimum fire return intervals (FRIs) from juvenile periods and post-fire recruitment success of overstorey proteoids (non-sprouting, slow-maturing, serotinous Proteaceae); and (v) determination of the ecologically appropriate fire season from post-fire recruitment seasonality of proteoids. I established that historically, plantation protection enjoyed priority over fynbos conservation in the area that is now the GRNP. Fynbos close to plantations has most likely been compromised by frequent and low-intensity burning in the past, as well as by invasion by alien trees. In terms of area burnt (1900–2010), natural (lightning-ignited) fires dominated the fire regime, particularly in the east, whereas prescribed burning was relatively unimportant. Typical fire return intervals (FRIs; 8–26 years; 1980–2010) were comparable to those in other fynbos protected areas and appeared to be shorter in the eastern Tsitsikamma than in the western Outeniqua halves of the study area. Proteaceae juvenile periods (4–9 years) and post-fire recruitment success (following fires in ≥7 year-old vegetation) suggested that for biodiversity conservation purposes, FRIs should be no less than nine years in moist, productive fynbos. Increases in the total area burnt annually (since 1980) were correlated with long-term increases in average fire danger weather, suggesting that fire regime changes may be related to global change. Collectively, findings on the seasonality of actual fires and the seasonality of fire danger weather, lightning, and post-fire proteoid recruitment suggested that fires in eastern coastal fynbos are not limited to any particular season, and for this reason managers do not need to be concerned if fires occur in any season. The ecological requirements for higher fire intensity may nonetheless be constrained by a need for safety. I articulated these findings into ecological thresholds pertaining to the different elements of the fire regime in eastern coastal fynbos, to guide adaptive management of fire in the Garden Route National Park. I also recommended a fire management strategy for the park to address the aforementioned operational considerations within the constraints posed by ecological thresholds. Finally, I highlighted further research and monitoring needs.
- Full Text:
- Date Issued: 2012
Force of habit the mystical foundations of the narcotic
- Authors: Howell, Simon Peter
- Date: 2012
- Subjects: Drug addiction -- Philosophy -- Research Drug addiction -- Political aspects -- Research Cocaine abuse -- Legal status, laws, etc. -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2784 , http://hdl.handle.net/10962/d1002994
- Description: This thesis aims to investigate and deconstruct the relationship between the narcotic, its narrative, and western modernity. To reveal the relationship, this thesis argues that it is possible to understand the philosophical, political, cultural and ethical dimensions of western modernity through the ulterior lens of the narcotic. As such, this thesis investigates western modernity's relationship to (a) cocaine as a specific narcotic, and (b) the concept of the narcotic with all its attendant connotations of addictions, illegitimacy, transgression, illegality, and so on. Accordingly, the thesis is both interpretive of the historical narrative of the narcotic of cocaine, and generative in its deconstruction of the relationship between western modernity and the concept of the narcotic. The deconstruction of this relationship ultimately reveals both prior narratives not as oppositional, but as supplementary. This has radical consequences for the manner in which we engage with narcotic use and the user - if the narcotic is supplement to the logic of western modernity, at each attempt to expel the use and user of the narcotic, rather then create difference, we self implicate ourselves in that expulsion and distance. To seek a new and more just means of dealing with the concept of the narcotic, and its use, therefore requires a new epistemological framework which can at once contemplate both narratives at the same time. To this end, the thesis suggests the use of critical complexity theory as one such methodological tool, if supplemented by the thoughts and strategies of Derridian deconstruction and Foucauldian discourse analysis.
- Full Text:
- Date Issued: 2012
- Authors: Howell, Simon Peter
- Date: 2012
- Subjects: Drug addiction -- Philosophy -- Research Drug addiction -- Political aspects -- Research Cocaine abuse -- Legal status, laws, etc. -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2784 , http://hdl.handle.net/10962/d1002994
- Description: This thesis aims to investigate and deconstruct the relationship between the narcotic, its narrative, and western modernity. To reveal the relationship, this thesis argues that it is possible to understand the philosophical, political, cultural and ethical dimensions of western modernity through the ulterior lens of the narcotic. As such, this thesis investigates western modernity's relationship to (a) cocaine as a specific narcotic, and (b) the concept of the narcotic with all its attendant connotations of addictions, illegitimacy, transgression, illegality, and so on. Accordingly, the thesis is both interpretive of the historical narrative of the narcotic of cocaine, and generative in its deconstruction of the relationship between western modernity and the concept of the narcotic. The deconstruction of this relationship ultimately reveals both prior narratives not as oppositional, but as supplementary. This has radical consequences for the manner in which we engage with narcotic use and the user - if the narcotic is supplement to the logic of western modernity, at each attempt to expel the use and user of the narcotic, rather then create difference, we self implicate ourselves in that expulsion and distance. To seek a new and more just means of dealing with the concept of the narcotic, and its use, therefore requires a new epistemological framework which can at once contemplate both narratives at the same time. To this end, the thesis suggests the use of critical complexity theory as one such methodological tool, if supplemented by the thoughts and strategies of Derridian deconstruction and Foucauldian discourse analysis.
- Full Text:
- Date Issued: 2012
Games as communication: an analysis of advertising in South Africa
- Authors: Wright, Bianca Maria-Teresa
- Date: 2012
- Subjects: Internet advertising , Branding (Marketing)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8417 , http://hdl.handle.net/10948/d1012929
- Description: Games as a form of communication have been examined by academics in the fields of game studies, narratology and media studies, among others, but the use of games to communicate advertising messages has not been adequately explored within the South African context. The study sought to investigate the phenomenon of advergaming, purpose-built games designed to communicate an advertising message, in South Africa, and to develop a model for the use of advergaming as a viral marketing tool in this context. Using a hybrid approach, the study examined the way that advertising agencies currently use advergames as well as the effectiveness of advergaming as a means to communicate a message. The study presents the results of a national survey of advertising agencies in South Africa, a content analysis of existing advergames and an analysis of three semi-structured group interview experiments conducted using selected advergames. The findings point to the potential of advergaming as a message communication tool, but also highlight the challenges that may hamper the widespread use of advergaming in South Africa. It proposes the use of the mobile environment as a means to reach a wider South African audience and in that way, overcome some of the obstacles to advergaming adoption. In addition, the results identify aspects of advergames that seem to correlate with the effectiveness of message communication.
- Full Text:
- Date Issued: 2012
- Authors: Wright, Bianca Maria-Teresa
- Date: 2012
- Subjects: Internet advertising , Branding (Marketing)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8417 , http://hdl.handle.net/10948/d1012929
- Description: Games as a form of communication have been examined by academics in the fields of game studies, narratology and media studies, among others, but the use of games to communicate advertising messages has not been adequately explored within the South African context. The study sought to investigate the phenomenon of advergaming, purpose-built games designed to communicate an advertising message, in South Africa, and to develop a model for the use of advergaming as a viral marketing tool in this context. Using a hybrid approach, the study examined the way that advertising agencies currently use advergames as well as the effectiveness of advergaming as a means to communicate a message. The study presents the results of a national survey of advertising agencies in South Africa, a content analysis of existing advergames and an analysis of three semi-structured group interview experiments conducted using selected advergames. The findings point to the potential of advergaming as a message communication tool, but also highlight the challenges that may hamper the widespread use of advergaming in South Africa. It proposes the use of the mobile environment as a means to reach a wider South African audience and in that way, overcome some of the obstacles to advergaming adoption. In addition, the results identify aspects of advergames that seem to correlate with the effectiveness of message communication.
- Full Text:
- Date Issued: 2012
Growth and characterization of ZnO nanorods using chemical bath deposition
- Authors: Urgessa, Zelalem Nigussa
- Date: 2012
- Subjects: Zinc oxide , Photoluminescence , Semiconductor nanocrystals , Semiconductors -- Materials , Chemical reactions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10559 , http://hdl.handle.net/10948/d1021124 , http://hdl.handle.net/10948/d1021119
- Description: Semiconductor devices are commonplace in every household. One application of semiconductors in particular, namely solid state lighting technology, is destined for a bright future. To this end, ZnO nanostructures have gained substantial interest in the research community, in part because of its requisite large direct band gap. Furthermore, the stability of the exciton (binding energy 60 meV) in this material, can lead to lasing action based on exciton recombination and possibly exciton interaction, even above room temperature. Therefore, it is very important to realize controllable growth of ZnO nanostructures and investigate their properties. The main motivation for this thesis is not only to successfully realize the controllable growth of ZnO nanorods, but also to investigate the structure, optical and electrical properties in detail by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy (steady state and time resolved) and X-ray diffraction (XRD). Furthermore, strong rectification in the ZnO/p-Si heterojunction is demonstrated. Nanorods have been successfully synthesized on silicon by a two-step process, involving the pre-coating of the substrate by a seed layer, followed by the chemical bath deposition of the nanorods. ZnO seed layers with particle sizes of about 5 nm are achieved by the thermal decomposition of zinc acetate dihydrate dissolved in ethanol. The effects of the seed layer density on the distribution, alignment and uniformity of subsequently grown nanorods were studied. The aspect ratio, orientation and distribution of nanorods are shown to be well controlled through adjusting the density of the ZnO nanoparticles pre-coated onto the substrates. It is shown that the seed layer is a prerequisite for the growth of well aligned ZnO nanorods on lattice mismatched Si substrate. The influence of various nanorod growth parameters on the morphology, optical and electrical properties of the nanorods were also systematically studied. These include the oxygen to zinc molar ratio, the pH of the growth solution, the concentration of the reactants, the growth temperature and growth time, different hydroxide precursors and the addition of surface passivating agents to the growth solution. By controlling these xii parameters different architectures of nanostructures, like spherical particles, well aligned nanorods, nanoflowers and thin films of different thicknesses are demonstrated. A possible growth mechanism for ZnO nanostructures in solution is proposed. XRD indicated that all the as-grown nanostructures produced above 45 C crystallize in the wurtzite structure and post growth annealing does not significantly enhance the crystalline quality of the material. In material grown at lower temperature, traces of zinc hydroxide were observed. The optical quality of the nanostructures was investigated using both steady-state PL and time-resolved (TR) PL from 4 K to room temperature. In the case of as-grown samples, both UV and defect related emissions have been observed for all nanostructures. The effect of post-growth annealing on the optical quality of the nanostructures was carefully examined. The effect of annealing in different atmospheres was also investigated. Regardless of the annealing environment annealing at a temperature as low as 300 C enhances the UV emission and suppresses defect related deep level emission. However, annealing above 500 C is required to out-diffuse hydrogen, the presence of which is deduced from the I4 line in the low temperature PL spectra of ZnO. TRPL was utilized to investigate lifetime decay profiles of nanorods upon different post growth treatments. The bound exciton lifetime strongly depends on the post-growth annealing temperature: the PL decay time is much faster for as grown rods, confirming the domination of surface assisted recombination. In general, the PL analysis showed that the PL of nanorods have the same characteristics as that of bulk ZnO, except for the stronger contribution from surface related bound excitons in the former case. Surface adsorbed impurities causing depletion and band bending in the near surface region is implied from both time resolved and steady state PL. Finally, although strong rectification in the ZnO/p-Si heterojunction is illustrated, no electroluminescence has been achieved. This is explained in terms of the band offset between ZnO and Si and interfacial states. Different schemes are proposed to improve the performance of ZnO/Si heterojunction light emitting devices.
- Full Text:
- Date Issued: 2012
- Authors: Urgessa, Zelalem Nigussa
- Date: 2012
- Subjects: Zinc oxide , Photoluminescence , Semiconductor nanocrystals , Semiconductors -- Materials , Chemical reactions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10559 , http://hdl.handle.net/10948/d1021124 , http://hdl.handle.net/10948/d1021119
- Description: Semiconductor devices are commonplace in every household. One application of semiconductors in particular, namely solid state lighting technology, is destined for a bright future. To this end, ZnO nanostructures have gained substantial interest in the research community, in part because of its requisite large direct band gap. Furthermore, the stability of the exciton (binding energy 60 meV) in this material, can lead to lasing action based on exciton recombination and possibly exciton interaction, even above room temperature. Therefore, it is very important to realize controllable growth of ZnO nanostructures and investigate their properties. The main motivation for this thesis is not only to successfully realize the controllable growth of ZnO nanorods, but also to investigate the structure, optical and electrical properties in detail by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy (steady state and time resolved) and X-ray diffraction (XRD). Furthermore, strong rectification in the ZnO/p-Si heterojunction is demonstrated. Nanorods have been successfully synthesized on silicon by a two-step process, involving the pre-coating of the substrate by a seed layer, followed by the chemical bath deposition of the nanorods. ZnO seed layers with particle sizes of about 5 nm are achieved by the thermal decomposition of zinc acetate dihydrate dissolved in ethanol. The effects of the seed layer density on the distribution, alignment and uniformity of subsequently grown nanorods were studied. The aspect ratio, orientation and distribution of nanorods are shown to be well controlled through adjusting the density of the ZnO nanoparticles pre-coated onto the substrates. It is shown that the seed layer is a prerequisite for the growth of well aligned ZnO nanorods on lattice mismatched Si substrate. The influence of various nanorod growth parameters on the morphology, optical and electrical properties of the nanorods were also systematically studied. These include the oxygen to zinc molar ratio, the pH of the growth solution, the concentration of the reactants, the growth temperature and growth time, different hydroxide precursors and the addition of surface passivating agents to the growth solution. By controlling these xii parameters different architectures of nanostructures, like spherical particles, well aligned nanorods, nanoflowers and thin films of different thicknesses are demonstrated. A possible growth mechanism for ZnO nanostructures in solution is proposed. XRD indicated that all the as-grown nanostructures produced above 45 C crystallize in the wurtzite structure and post growth annealing does not significantly enhance the crystalline quality of the material. In material grown at lower temperature, traces of zinc hydroxide were observed. The optical quality of the nanostructures was investigated using both steady-state PL and time-resolved (TR) PL from 4 K to room temperature. In the case of as-grown samples, both UV and defect related emissions have been observed for all nanostructures. The effect of post-growth annealing on the optical quality of the nanostructures was carefully examined. The effect of annealing in different atmospheres was also investigated. Regardless of the annealing environment annealing at a temperature as low as 300 C enhances the UV emission and suppresses defect related deep level emission. However, annealing above 500 C is required to out-diffuse hydrogen, the presence of which is deduced from the I4 line in the low temperature PL spectra of ZnO. TRPL was utilized to investigate lifetime decay profiles of nanorods upon different post growth treatments. The bound exciton lifetime strongly depends on the post-growth annealing temperature: the PL decay time is much faster for as grown rods, confirming the domination of surface assisted recombination. In general, the PL analysis showed that the PL of nanorods have the same characteristics as that of bulk ZnO, except for the stronger contribution from surface related bound excitons in the former case. Surface adsorbed impurities causing depletion and band bending in the near surface region is implied from both time resolved and steady state PL. Finally, although strong rectification in the ZnO/p-Si heterojunction is illustrated, no electroluminescence has been achieved. This is explained in terms of the band offset between ZnO and Si and interfacial states. Different schemes are proposed to improve the performance of ZnO/Si heterojunction light emitting devices.
- Full Text:
- Date Issued: 2012
Histopathological changes in male wistar rats maintained on a water-based sutherlandia frutescens extract
- Authors: Wickens, Nicolas John
- Date: 2012
- Subjects: Rats -- Physiology , Rats as laboratory animals
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/4742 , vital:20670
- Description: In this study a standardized 46 week chronic drinking water toxicity protocol was used to elucidate the toxic potential of Sutherlandia frutescens (S. frutescens) using histopathologic, morphometric and transmission electron microscopic analysis. The histopathologic changes in the duodenum, heart, kidney, liver, lung, pancreas and spleen of male Wistar rats were evaluated. Fifty-four rats were randomly divided into four groups: Group 1 – Normal diet control (ND control), n=7, Group 2 – Normal diet + plant extract (ND + p), n=9, Group 3 – High fat diet control (HFD control), n=19Group 4 – High fat diet + p (HFD + p), n=19In the high fat group male Wistar rats were fed ±55 g/day of a specialised high fat diet over a 46 week period to induce obesity and an insulin resistant state. The treatment groups (groups 2 and 4) received a dose concentration of a tea extract of the S. frutescens plant in their drinking water daily. This study showed that the consumption of S. frutescens significantly reduces weight gain in male Wistar rats on a chronic high fat diet (p≤0.001 vs. HFD control group). S. frutescens appears to propagate periportal and centrilobular glycogen storage in rat hepatocytes in the experimental groups as exemplified by a significantly (p≤0.0001 vs. control groups) increased incidences of Periodic Acid Schiff (PAS) positive staining S. frutescens also reduced intracellular lipid accumulation as made evident by the significantly lower incidence of epicardial adipose tissue (EAT), hepatic steatosis and pancreatic interstitial fat. Obesity was associated with increased fibrotic lesions such as myocardial perivascular fibrosis, centrilobular hepatic fibrosis and pancreatic periductal fibrosis. Obesity associated hypertension contributed to the widespread and significant increase in the average lesion severity of arterial congestion in all organs in the HFD control group. Pulmonary infection was equally prevalent in all rats. Despite the complex histopathology in all groups, differences in the control groups, such as, the presence of a conservative polymorphonuclear leukocyte (PMNL) infiltration, substantial intra-alveolar oedema and focal arterial wall hypertrophy in the control groups was highly suggestive of Sendai viral infection. However histopathologic evidence, in the treatment groups, suggested chronic recurrent viral infection with superimposed Mycoplasma pulmonis (M. pulmonis) bacterial infection. The impact of advanced suppurative pulmonary infection was widespread and exemplified by increased lesion incidences of spontaneous murine progressive cardiomyopathy (MCP) and spontaneous chronic progressive nephropathy (CPN) among others. In conclusion S. frutescens administered for 46 weeks to male Wistar rats significantly lowered intracellular lipid accumulation and obesity associated myocardial, renal, hepatobiliary, pulmonary and pancreatic histopathology. Moreover, duodenal, cardiovascular, hepatobiliary, pulmonary, renal, pancreatic and splenic tissue did not show histopathologic evidence of direct plant extract associated toxicity or carcinogenicity.
- Full Text:
- Date Issued: 2012
- Authors: Wickens, Nicolas John
- Date: 2012
- Subjects: Rats -- Physiology , Rats as laboratory animals
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/4742 , vital:20670
- Description: In this study a standardized 46 week chronic drinking water toxicity protocol was used to elucidate the toxic potential of Sutherlandia frutescens (S. frutescens) using histopathologic, morphometric and transmission electron microscopic analysis. The histopathologic changes in the duodenum, heart, kidney, liver, lung, pancreas and spleen of male Wistar rats were evaluated. Fifty-four rats were randomly divided into four groups: Group 1 – Normal diet control (ND control), n=7, Group 2 – Normal diet + plant extract (ND + p), n=9, Group 3 – High fat diet control (HFD control), n=19Group 4 – High fat diet + p (HFD + p), n=19In the high fat group male Wistar rats were fed ±55 g/day of a specialised high fat diet over a 46 week period to induce obesity and an insulin resistant state. The treatment groups (groups 2 and 4) received a dose concentration of a tea extract of the S. frutescens plant in their drinking water daily. This study showed that the consumption of S. frutescens significantly reduces weight gain in male Wistar rats on a chronic high fat diet (p≤0.001 vs. HFD control group). S. frutescens appears to propagate periportal and centrilobular glycogen storage in rat hepatocytes in the experimental groups as exemplified by a significantly (p≤0.0001 vs. control groups) increased incidences of Periodic Acid Schiff (PAS) positive staining S. frutescens also reduced intracellular lipid accumulation as made evident by the significantly lower incidence of epicardial adipose tissue (EAT), hepatic steatosis and pancreatic interstitial fat. Obesity was associated with increased fibrotic lesions such as myocardial perivascular fibrosis, centrilobular hepatic fibrosis and pancreatic periductal fibrosis. Obesity associated hypertension contributed to the widespread and significant increase in the average lesion severity of arterial congestion in all organs in the HFD control group. Pulmonary infection was equally prevalent in all rats. Despite the complex histopathology in all groups, differences in the control groups, such as, the presence of a conservative polymorphonuclear leukocyte (PMNL) infiltration, substantial intra-alveolar oedema and focal arterial wall hypertrophy in the control groups was highly suggestive of Sendai viral infection. However histopathologic evidence, in the treatment groups, suggested chronic recurrent viral infection with superimposed Mycoplasma pulmonis (M. pulmonis) bacterial infection. The impact of advanced suppurative pulmonary infection was widespread and exemplified by increased lesion incidences of spontaneous murine progressive cardiomyopathy (MCP) and spontaneous chronic progressive nephropathy (CPN) among others. In conclusion S. frutescens administered for 46 weeks to male Wistar rats significantly lowered intracellular lipid accumulation and obesity associated myocardial, renal, hepatobiliary, pulmonary and pancreatic histopathology. Moreover, duodenal, cardiovascular, hepatobiliary, pulmonary, renal, pancreatic and splenic tissue did not show histopathologic evidence of direct plant extract associated toxicity or carcinogenicity.
- Full Text:
- Date Issued: 2012